lib: write: Remove unused variable.
lib: utf16: Fix const-correctness issues in _hivex_recode function.

This patch assumes that iconv doesn't actually modify the
input buffer, even though it is declared as char *.
lib: Add internal function to calculate strlen for strings encoded in Latin1 or UTF-16LE
lib: Mind character encoding in value_key_len, add matching node_name_len function

Since iconv() does not treat null characters as special, this makes it
possible to read node names and value keys with embedded null
characters. which are not displayed at all by Windows Regedit.
generator: use node_name_len, value_key_len API in bindings
Fix const-correctness in _hivex_utf8_strlen function.

Plus a whitespace fix.